One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,9)(8,10)(11,12)(15,22)(20,23)(24,26)(25,28) involution — undirected(1,2,4,3)(5,7)(6,9)(8,11)(10,12)(13,14)(15,23)(16,17)(18,21)(19,27)(20,22)(24,28)(25,26)(6,10)(7,11)(13,15)(14,20)(16,26)(17,28)(18,22)(19,25)(21,23)(24,27) involution — undirected(6,10)(9,12)(13,16,17,14,18,27,19,21)(15,24,28,23,22,26,25,20)(1,3,4,2)(13,17,18,19)(14,16,21,27)(15,25,22,28)(20,24,23,26)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.